TECHNICAL ARTICLE

AS PUBLISHED IN The Journal October 2018 Volume 136 Part 4

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Alison Stansfield MARKETING DIRECTOR Permanent Way Institution [email protected]

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HSGT Systems: AUTHOR:

Manuel Contreras HSR, and Stanway Consulting

INTRODUCTION However, they all have a potential operational force is generated producing the levitation speed in excess of 218mph, see table 1. of the train. Sensors in the train regulate the The need for high speed transportation current in the coils, maintaining a 1cm gap from systems has intensified in recent decades. HIGH-SPEED RAIL (WHEEL-RAIL) the guideway. Electromagnets placed on both All industrialised countries have faced two L-shaped arms of the train are responsible for serious transportation problems in urbanised High-speed rail (HSR) is a type of rail the centering of the train on the track. regions and in major intercity corridors; Firstly, transport that operates significantly faster highway and street congestion, causing long than traditional rail traffic, using an integrated DISADVANTAGES travel times, economic inefficiencies, and system of specialised rolling stock and deterioration of the environment and quality dedicated tracks. There is no single standard Dynamic Instability: Magnetic attraction varies of life. Secondly, rising congestion at airports, that applies worldwide, but new lines in excess inversely with the cube of distance, so minor with similar social and economic costs. of 250 km/h (160 mph) and existing lines in changes in the magnets and the rail produce excess of 200 km/h (124 mph) are considered greatly varying forces. These changes in force High-Speed Ground Transportation systems to be high-speed, with some extending are dynamically unstable; a slight divergence (HSGT) is one way to address these issues, the definition to include lower speeds in from the optimum position tends to increase, improve connectivity, encourage development, areas for which these speeds still represent requiring sophisticated feedback systems to enhance business opportunities and provide an significant improvements. High-speed trains maintain a constant distance from the track. alternative transportation mode. This concept normally operate on standard gauge tracks of emerged as the inclusion of two systems; high- continuously welded rail on grade-separated High precision required in the construction of speed railways (HSR) and right-of-way that incorporates a large turning the guideway. trains (Maglev). radius in its design. Susceptible to earthquakes. Both HSR and Maglev, are physically guided LINES IN OPERATION systems on fully controlled ways with fail-safe MAJOR ADVANTAGES OVER EDS electronic signal control. This provides not 29,792km of High Speed lines in the world only an order of magnitude of high safety (1 April 2015) The EMS system works at all speeds and but also reliable operation even under eliminates the need for a separate low-speed capacity conditions and a reduction in carbon MAGNETIC LEVITATION suspension system, simplifying the track layout. emissions. In addition to these systems, Elon (MAGLEV) Musk, CEO at Space X and Tesla, announced a new fixed-guideway intercity transport mode ELECTRODYNAMIC SUSPENSION SYSTEM The Maglev system consists of four main called Hyperloop in 2013. (EDS) components: guideway, vehicle, power supply and operation control system. Maglev HSGT is an efficient means for transporting The EDS system is based on vehicles use noncontact magnetic levitation, large passenger volumes with high speed, superconductivity, which is a quantum guidance and propulsion systems and have no reliability, passenger comfort, and safety. mechanical phenomenon of the exact zero wheels, axles and transmission. The common electrical resistance and repulsion of magnetic point in all applications is the lack of contact Any proposal for the introduction of a new fields (Meissner Effect), occurring in certain and therefore there is no wear and friction. transportation mode requires a complete materials, called superconductors, when This increases energy efficiency, reduces analysis that should address among others the cooled (e.g: liquid nitrogen, liquid helium) below maintenance costs, and increases the useful questions in image 1. a characteristic critical temperature (T

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Image 1

Table 1: Overview of HSR, Maglev and Hyperloop systems Image 2: B = Magnetic field. Diagram of the Meissner Effect

Image 3: Electrodynamic suspension system (EDS)

DISADVANTAGES INDUCTRACK (PASSIVE MAGLEV) HYPERLOOP Inductrack is an EDS system that uses Need for a separate low-speed suspension unpowered loops of wire in the track and Hyperloop is a concept and proposed system: Due to the train requiring wheels to permanent magnets on the vehicle. The transportation system for passenger and/ support the train until it reaches levitating magnets, which are required to produce the or freight using magnetic propulsion to carry speed, the entire track must be able to support necessary magnetic fields instead of using vehicles/pods through partial-vacuum tubes to both low- and high-speed operation. electromagnets or superconducting magnets, offer high speed inter-city transport. The main are arranged into a so-called Halbach array goal of the concept is to reduce air resistance MAJOR ADVANTAGES OVER EMS which concentrates the magnetic field intensity and friction to achieve very high speeds (near- below the array and cancels out above it. sonic speeds over 760 mph; 1,100 km/h) and Dynamic Stability: Changes in distance Additionally, the train has auxiliary wheels moderate energy consumption. between the track and the magnets create which can be used at lower speeds in case of strong forces to return the system to its original system failure, see table 4. position, see table 3.

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The main technologies used in Hyperloop are: CURRENT DEVELOPMENT AND Current railway research and development FUTURE CHALLENGES programs aim to achieve higher operational • Partial-vacuum tubes to reduce speeds combined with lower aerodynamic

environmental pressure and air resistance resistance and new energy transmission HIGH-SPEED RAIL on pods. systems. In the coming years, high- speed rail will also make improvements in The first high speed rail began operations in • Passive magnetic levitation (Inductrack) standardisation and modularity of rolling Japan in 1964 (Shinkanshen – “Bullet Train”) to reduce friction of the vehicles. stock, new braking systems, improvements to and HSR lines have been in operation since make it more environmentally friendly (noise, then demonstrating excellent efficiency and • (LIM) as a energy efficiency) and new technologies safety, attracting passengers and improving propulsion and braking system. (telecommunications, WI-FI, etc.) economic efficiency. Compatibility of the rail

systems is fundamental for the creation of • Vehicles/pods to transport passengers MAGLEV an integrated international network of high and/or freight. speed ground transportation lines. Maximum Maglev is another technology for guided operating speed is the most important feature LINES IN OPERATION transportation systems with strong public of this system. appeal because of its unique feature: the • Two test tracks have been built to test the vehicles are supported, guided and propelled However, developments in high-speed rail have technology: by magnetic forces, so there is no physical historically been impeded by the difficulties contact between wheels and guideway in managing friction and air resistance, both • SpaceX’s test facility in California surfaces. Maglev systems can be considered of which become substantial when vehicles (1,25km) technically and operationally feasible and are approach high speeds. presumed to have certain advantages over • Hyperloop One’s “DevLoop,” in Nevada HSR. (500m))

Table 2. Comparison between EMS and EDS systems

Table 3. Examples of Maglev Lines

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The two versions of this system, EMS and Another advantage is that noise generated by implementing advanced light-weight materials EDS, offer higher speeds than HSR, due to air friction and turbulence is greatly reduced to reduce the weight of the vehicles. the acceleration and deceleration times, which with maglev trains. At speeds under 200 km/h, imply shorter travel time. maglev systems can hardly be heard, an If guideway power is lost, the is still important advantage in urban and populated able to generate levitation, using the power In the areas of travel comfort and safety, the areas. from onboard batteries. This is not the case of design of the guideways ensures that the trains the Chuo Shinkanshen that needs the use of are protected from derailment. In addition, the However, maglev infrastructures are expensive wheels at speeds below 100 km/h. levitation of the vehicle ensures a quiet and to build, because of the dedicated and singular smooth ride even at high speeds, reducing infrastructure, and to operate due to the Each maglev system has its own advantages mechanical friction during operation and expensive computer systems required for that can be applied for different uses, e.g. high- consequently maintenance costs. monitoring magnetic separation in the case of speed passenger and freight transport or as a EMS system and the significant cost for cooling local urban commuter system. For topographically demanding routes, maglev superconductor magnets in the EDS system. trains offer some advantages. Some Maglev HYPERLOOP systems can cope with gradients up to 10% On the other hand, the drive mechanism lies in and more (e.g. Transrapid maglev), adapting the guideway and is not carried in the vehicle Hyperloop is an “open-sourced” concept more easily to the landscape and offering but the weight of the large electromagnets in for a near-sonic, fixed-guideway, intercity savings in infrastructure construction. In the many maglev vehicles is a major design issue. transportation system using capsule-like case of elevated track, alternative uses of land For this reason, one research line is using vehicles, usually called pods, that operate in under the track are also possible. superconductors and another research path is partial vacuum tubes.

Table 4. Comparison of HSR, Maglev and Hyperloop Technologies

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The idea of travelling through evacuated system malfunction, capsule depressurisation, system to be competitive beyond the next 20 tubes was initially devised in 1799 in the vulnerability to environmental hazards (e.g. years. Maglev systems have some advantages United Kingdom by George Medhurst by using earthquakes) and others such as vandalism over HSR. These systems are more energy compressed air, but never was constructed. or terrorism, accident severity because of efficient, produce less noise, possess better A similar design by Vallance in 1824 was the kinematic energy of the capsule and operational performance (because of their devised and a test site constructed but never comfort for passengers. All these issues make acceleration and deceleration times), and are put into commercial operation. The Hyperloop the transport of goods to be in a position safer than HSR. However, the infrastructure technology is recent and currently unproven, of preference when it comes to testing the construction cost, energy and systems required but it has attracted attention from journalists, technology and its performance in operations. for their operation is aggravated in the case of investors, engineering firms and governments. Hyperloop technology cost estimates (£17.55- Maglev. One research approach is focussed 19.05 million per mile) appear lower than other on reducing cost for cooling superconductor A few companies and several interdisciplinary modes (e.g. HSR in Europe, £18.346-53.75 and another research approach is on advanced student-led teams are working to develop million per mile), but as the technology is still light-weight materials to reduce the weight of the technology. Some governments have conceptual and in very initial stages, there is the vehicles. also commissioned feasibility studies, uncertainty in both the infrastructure needed to demonstrating their growing interest in the operate the system and the cost to construct it. Hyperloop technology is a highly innovative subject. There are currently two test tracks transportation mode that could enable the to evaluate the technology but the different Some of the elements that would have an highest ground transportation speeds. technologies on which Hyperloop is based impact on infrastructure costs are: land However, the development of the technology is (partially evacuated tubes, pods, passive acquisition; infrastructure construction still in its early stages, there are engineering, maglev, linear induction motors…) have (elevated, underground, submerged); stations economic, safety and social challenges to different degrees of development and a full- (as it will require new and independent overcome and it will require coordination scale system will be required to validate the stations); levitation, propulsion and braking and acceptance from regulatory agencies on feasibility and operability of an integrated systems (Inductrack, linear induction motor); design, operations, security, and safety. system. tubes (diameter, material, thickness, expansion Finally, the implementation of a new joints; bearings, vacuum pumps, installation infrastructure has many economic, social and Hyperloop technology is claimed by its costs, etc). environmental implications, not only for today’s developers to be the fifth mode of transport, society, but also for future generations. One of faster than existing forms for intercity Operating and maintenance costs will depend the main objectives should be to evaluate the passenger travel (air, HSR and Maglev) and on energy consumption and efficiency, number new transport system in context with existing able to provide the service at lower cost and type of pods (passenger and/or freight) infrastructure, available resources, considering than high-speed rail. However, there are required, traffic control systems, …In terms the development of new technologies and engineering and operational challenges, of interoperability, hyperloop operates in a attending not only to initial construction economic, safety, regulatory and political, and partially vacuum environment, reducing the costs but also to long-term operation and environmental issues to overcome before it ability to provide interoperability with other maintenance costs, to provide a new efficient, becomes a reality. modes of transport. safe, sustainable, reliable and high-capacity transportation system that meets the current Some of the engineering and technical Environmental impacts such as power source, and future needs of society. challenges to consider are related to the efficiency of energy consumption, full life cycle thermal expansion of the tube (design emissions, visual impact, are also factors REFERENCES and location of the expansion joints); to consider. Additionally, a completely new appropriate sub-systems for levitation, transportation mode would pose a unique set Wikipedia propulsion and braking; structural behaviour of regulatory and policy issues and that would of the infrastructure and vulnerability to also need to be resolved. “The Most Important Maglev Applications”, environmental hazards; challenges related Hamid Yaghoubi to fluid dynamics (design of the capsule, It should also be noted that in the case where diameter of the tube and capsule, Kantrowitz stations were located on the outskirts of major “An evaluation of Maglev Technology and its limit,…); geometric constrains of the alignment cities, travellers would require additional time comparison with High Speed Rail”, Vukan (vertical and horizontal) and location of on local transit to reach their final destination. Vuchic and Jeffrey M. 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Study”, Washington State Department of CONCLUSION Transportation, CH2M Performance in operations will be closely related to the operational speed (an average Three systems have been explained in this “Railway Engineering, UNED”, Francisco Javier of 600mph), maximum acceleration and paper and are based on different concepts and González Fernández and Julio Fuentes Losa. deceleration, frequency, number and capacity technologies with different current and future of the capsules required to accommodate peak challenges. “Hyperloop: Concept, Technologies and demand; times for departures and arrivals Business Model (S260)”, Rail Safety and (including alighting and boarding); number of High Speed Railways can offer attractive Standards Board Ltd, RSSB. tubes needed to ensure operation as well as in travel times, high capacity, frequency, case of emergency or maintenance operations. accessibility, comfort, reliability and safety as “The future of Rail: Evolution and Perspectives Operational scheme; alignment; type of well as interconnectivity and interoperability. of High-Speed Rail, Maglev and Hyperloop”, transport (passengers and/or freight); station Developments in high-speed rail have Esther González-González, Soledad Nogués configuration,are also factors to consider. historically been impeded by the difficulties in managing friction and air resistance, both The International Maglev Board Furthermore, due to the high speeds in a of which become substantial when vehicles partially vacuum tube there are also important approach high speeds. 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